1. Field of the Invention
The present invention relates to a golf club.
2. Description of the Related Art
Hitherto when a golf club comprising a head and a shaft is assembled, the shaft is processed rough on the surface of a distal portion thereof, and is fitted with a truncated-cone-shaped, socket-like ferrule, while protruding the shaft itself from the ferrule by a suitable length to be bonded. Thereafter, epoxy-based resin or the like is normally applied to the portion of a shaft to be bonded so that the shaft is fixed to the head. The distal portion of the shaft has a diameter which is about 0.1 mm smaller than an inside diameter of a shaft insertion hole formed in a hosel, in order that an adhesive may be ensured to be present between the hosel and the shaft. Although a gap between the shaft insertion hole in the hosel and the shaft is very narrow, it is very difficult to allow the central axis of the shaft to precisely align with that of the hosel due to this narrow gap, and thus the shaft occasionally is fitted at an offset position and/or inclined toward a certain direction. As a result, such golf club is subjected to changes in angles including loft, lie and face angles after assembling, even though these angles were each in accordance with designed values at the time of the completion of the head. Whilst an adhesive should desirably be applied uniformly to an area for adhesion and then be hardened because one can obtain the highest strength by doing so, there is the possibility, if the gap is not uniform, that the adhesive strength might be reduced and the head get detached from the shaft during the use of the golf club.
For this type of a golf club, Japanese Un-Examined Patent Publication Number 10-314345 discloses a golf club in which a distal end of a shaft is fitted to a hosel in such a manner that the hosel is formed with a stepped peripheral surface, through which the distal end of the shaft is inserted from the outside into the hosel, while a ring made of plastic is bonded to said stepped peripheral surface so that the separation of the shaft from the head may be prevented.
According to the above prior art, the improvement of the joint strength between the head and the shaft is aimed at, using the ring, which, however, has a drawback that it is often very difficult to adjust so as to have the central axis of the shaft precisely align to that of the head, when connecting the shaft to the head, and thus there is a probability that angles including loft, lie and face angles are subjected to delicate changes after the head and the shaft are assembled together.
Accordingly, it is an object of the present invention to provide a golf club in which the axis of a shaft can be precisely aligned to that of a head when connecting them to each other, to thereby prevent loft, lie, face angles and etc of the club head from deviating from designed values.
It is another object of the present invention to provide a golf club with a high adhesive strength between the head and the shaft.
To attain the above objects, there is provided, according to a first aspect of the present invention, a golf club which comprises: a head having a hosel; a shaft insertion hole provided on a distal end face of said hosel; and a shaft fitted into said shaft insertion hole and bonded thereto with an adhesive, wherein said shaft insertion hole is formed with an enlarged portion formed in an opening portion thereof, while a ring body with a through-hole formed therethrough is provided in said enlarged portion so that said shaft may be inserted and penetrate therethrough.
According to the first aspect, the shaft is inserted into the shaft insertion hole while being guided by the ring body.
According to a second aspect of the present invention, there is provided a golf club as set forth in the first aspect, wherein said enlarged portion is provided in the form of a chamfered portion or a stepped portion so that an outer peripheral face of said ring body is fitted into said enlarged portion.
According to the structure of the second aspect, as the outer peripheral face of the ring body is fitted into and fixed by the chamfered portion or the stepped portion, the shaft can be guided well through said ring body.
According to a third aspect of the present invention, there is provided a golf club according to any of the foregoing aspect, wherein said ring body is made of rubber or plastic.
Accordingly, the ring body is elastically deformable at the time of striking a golf ball.